Magnesium Benefits

Magnesium for Leg Cramps – Does it Work?

Around 60% of adults and 7% of children experience leg cramps at some point. Some cases are mild and infrequent, but if you’re one of the many who experience leg cramps on a regular basis, you might be wondering: can magnesium help with leg cramps? 

The short answer is yes, but it depends on the cause. In this article, we’ll look at why leg cramps happen and when magnesium can help, but first — what exactly is magnesium? 

What is magnesium? 

Magnesium is an essential mineral that you need for optimal function. It’s involved in over 300 chemical processes in the body, but for the purposes of this article, we’ll focus on one of its most important roles… 

Magnesium is an electrolyte, which means it’s a mineral with an electrical charge. Among its many important jobs, it helps to regulate your body’s “electrical circuit”. That covers a whole host of functions, including communication between your nerves and muscles. 

Your muscle movements are controlled by electrical impulses sent from your nerves. The impulse causes the muscle to contract, and then the muscle relaxes when it stops. When you have a leg cramp or spasm, the muscle contracts but doesn’t relax. This is where muscle cramps get complicated…

The muscle needs magnesium to relax, so a lack of magnesium can cause cramps by preventing this important step. However, there are many other issues that could also contribute to muscle cramps. For example, a damaged nerve might not be able to stop sending electrical signals or may send signals that are way too strong. In other cases, the nerves and muscles might be short on other nutrients that they need to function properly. 

Can magnesium help with leg cramps? 

Because there are so many different reasons you might experience leg cramps, magnesium may help in some cases but not others. For example, if your leg cramps are due to a medication you’re taking, magnesium supplements are unlikely to help. But if you’re suffering from leg cramps due to strenuous exercise or muscular issues, there’s evidence to suggest that magnesium could offer you some relief. Here, we’ll go through some of the more common causes and how magnesium might help…

Exercise-induced cramps 

If you work out or play sports, you’ve undoubtedly experienced exercise-induced leg cramps in your calf muscles, quads, or hamstrings. It can happen during a workout or immediately after, and last anywhere from one to ten minutes, although your muscles might feel tender for up to 24 hours afterward. 

The cause of exercise-induced cramps is still up for debate, so let’s take a look at the most popular theories…

  • Dehydration – When you sweat during exercise, you lose electrolytes like magnesium. Remember that the muscles can’t relax without it, which might explain why they feel cramped. 
  • Muscle fatigue – Your muscles use glucose to create their preferred source of energy, a molecule called ATP. Not only does magnesium help to make more glucose available for this process during exercise, it also binds to the ATP molecule to make it usable. That’s why we need around 20% more magnesium during exercise. It would make sense that a lack of magnesium might make the muscle fatigue quicker, potentially causing it to go into spasm. 
  • Metabolic by-products – During strenuous exercise, your muscles use a process called anaerobic respiration to meet their increased ATP demands. This creates acidic by-products that can build up in the muscles, leading to a burning, cramping sensation. Magnesium helps to remove these by-products more efficiently. 
  • Neuromuscular control – The most recent theory is that heavy muscle overload and fatigue alter the nerve signals that control the muscle. An imbalance happens and the nerve becomes more excitable, sending stronger, faster signals to the muscle that are felt as cramps.

In each potential cause, it’s easy to see how magnesium — or magnesium deficiency — could play a role in exercise-induced leg cramps. Therefore, it stands to reason that taking a magnesium supplement may help to prevent or ease discomfort. 

For best results, opt for magnesium malate. It’s made with malic acid, another compound that increases the efficiency of cellular energy production and is known to boost exercise endurance and performance

Nocturnal leg cramps

For many people, leg cramps aren’t just a consequence of a good workout. Nighttime leg cramps can strike just as you’re settling down for bed, or even wake you up in the middle of the night. But if it’s not exercise, what’s causing them?

Well, nocturnal leg cramps do actually have a few things in common with exercise. First, they can last a short time but leave you tender for hours afterward. Second, nobody can agree on exactly what causes them! 

We know that you’re more likely to have nighttime leg cramps if you’re dehydrated, you sit or stand for long periods, or you’ve overworked your muscles during the day. That sounds an awful lot like the theories for exercise-induced cramps, suggesting that magnesium may be able to help here, too.

Restless legs 

Another nighttime affliction that might keep you awake is restless leg syndrome (RLS). RLS and leg cramps are not the same things, but RLS does cause uncomfortable sensations in the legs that can include cramps. This typically happens when you’re resting, and because movement offers relief, you’ll often have a strong urge to keep moving your legs. In kids, this might look like kicking out, wriggling, and generally having trouble staying still. 

Again, we don’t know exactly why people develop RLS, but there are certain risk factors that make it more likely. These include diabetes, iron deficiency, and peripheral nerve problems — all things that magnesium supplements can help to address. Let’s take a look at them one by one…

  • Diabetes – Low magnesium significantly increases your risk of developing diabetes. In turn, diabetes increases magnesium loss, creating a self-reinforcing cycle. A magnesium supplement can have a positive effect on blood sugar control and insulin sensitivity (as shown here, here, here, here, and here), making diabetes — and its associated complications — up to 47% less likely
  • Iron deficiency – Iron is used to make hemoglobin, the molecule that transports oxygen to your cells — muscle cells included. Malic acid can improve your absorption of certain types of iron found in the diet, indirectly boosting the oxygenation of the muscles. You can benefit from malic acid and magnesium by taking magnesium malate
  • Peripheral nerve problems – When peripheral nerves, i.e. those in the limbs and extremities, are damaged, they can cause ongoing pain, discomfort, and other sensations. Magnesium is essential for healthy nerve function and is often used by people suffering from nerve pain, so a supplement may also help in cases where RLS is caused by peripheral nerve problems. 

Chronic muscular pain 

Some people experience leg cramps as part of wider chronic pain problems like fibromyalgia. With all the muscle and nerve health benefits magnesium offers, it’s not surprising that people rave about magnesium supplements for helping with such conditions. 

Research supports this, with one study showing that magnesium malate significantly improved the pain symptoms of people with fibromyalgia. In another, patients reported improved muscle pain and fewer tender spots around the body after taking magnesium malate. 

Magnesium chloride has also been shown to reduce muscle pain in conditions like fibromyalgia. One case report discussed a 10-year-old boy who had suffered from debilitating health issues, including muscular pain, for most of his childhood. After many unsuccessful treatments, the boy found complete relief from his pain after being given magnesium glycinate. 

Muscle cramps in pregnancy 

Pregnancy is an exciting time, but some of the physical effects aren’t quite so fun! Leg cramps are very common in pregnancy for lots of reasons, like dehydration, muscle stress caused by extra weight, and the growing baby putting pressure on your nerves and blood vessels. 

Some research suggests that taking magnesium supplements can reduce the frequency and intensity of pregnancy-induced leg cramps, possibly by helping the muscles to relax and improving nerve function.

Which magnesium supplement should I take for leg cramps? 

There are many different types of magnesium supplements, but research suggests that magnesium malate and magnesium glycinate are especially good for leg cramps.

How much magnesium should I take for leg cramps?

The recommended magnesium dosage and intake vary depending on your age and sex. The table below shows the adequate intake (AI) and recommended dietary allowance (RDA) from the National Institute of Health.

Birth to 6 months30 mg*30 mg*
7–12 months75 mg*75 mg*
1–3 years80 mg80 mg
4–8 years130 mg130 mg
9–13 years240 mg240 mg
14–18 years410 mg360 mg
19–30 years400 mg310 mg
31–50 years420 mg320 mg
51+ years420 mg320 mg

Are magnesium supplements safe?

Yes, for most people. 

Exceeding the upper dosage is not necessarily dangerous for healthy people as the threshold for magnesium toxicity, or poisoning is much higher. However, taking more than this increases your risk for side effects like nausea, stomach cramps, and diarrhea. 

You should know that magnesium supplements can interact with some medications and change how they work. Some medical conditions can also affect how magnesium is absorbed and used in your body. If you take medications or you have a health condition, it’s important to check in with your doctor before using magnesium supplements to make sure they’re safe for you. 

Magnesium supplements are generally safe for pregnant women. In fact, they’re sometimes recommended to help expectant mums to meet their increased magnesium needs during pregnancy. However, if you’re planning to take magnesium supplements to help with your pregnancy leg cramps, it’s best to double-check with your doctor or midwife first.